Structure of the Nasal Septum
The nasal cavity (cavitas nasi) is divided into two symmetrical halves by the nasal septum (septum nasi). Its anatomical structure features three main parts:
- membranous part — pars membranacea
- cartilaginous part — pars cartilaginous
- bony part — pars ossea
The framework of the cartilaginous part is the septal nasal cartilage (cartilago septi nasi), which has an irregular quadrilateral shape. Its posterosuperior margin is firmly fixed, fitting into the angle between the perpendicular plate of the ethmoid bone and the vomer.
The base of the septum separates the nostrils and forms the mobile part of the nasal septum (pars mobilis septi nasi). Globally, the entire cavity is divided into the nasal vestibule (vestibulum nasi), which is lined with skin continuous with the external nose through the nares, and the nasal cavity proper (cavitas nasi), which is covered by mucous membrane.
Nasal Meatuses and Conchae
Paired nasal meatuses form within the nasal cavity, their boundaries defined by the nasal conchae:
- Superior nasal meatus (meatus nasi superior) — bounded by the superior and middle nasal conchae.
- Middle nasal meatus (meatus nasi medius) — located between the middle and inferior nasal conchae.
- Inferior nasal meatus (meatus nasi inferior) — situated between the inferior concha and the floor of the nasal cavity.
A space remains between the medial surfaces of all nasal conchae and the nasal septum, forming the common nasal meatus (meatus nasi communis). An important topographical feature is that the nasolacrimal duct (ductus nasolacrimalis) opens directly into the inferior nasal meatus.
Mucous Membrane of the Nasal Cavity
The mucous membrane of the nasal cavity proper is heterogeneous and divided into two functional zones:
- Respiratory region (pars respiratoria) — occupies the majority of the nasal cavity.
- Olfactory region (pars olfactoria) — localized in the superior part of the nasal septum and contains the endings of the olfactory nerves (nn. olfactorii).
The mucous membrane is very rich in mucous glands (glandulae nasales), especially within the respiratory region. A dense network of blood and lymphatic vessels lies within the submucosa. In the region of the inferior and middle nasal conchae, these vessels form massive cavernous plexuses (plexus cavernosi concharum).
Blood Supply, Venous Drainage, and Innervation
Blood supply to the nasal cavity is provided by branches of several major arteries:
- Sphenopalatine artery (a. sphenopalatina)
- Maxillary artery (a. maxillaris)
- Anterior and posterior ethmoidal arteries (aa. ethmoidales anterior et posterior)
Venous blood from the walls of the nasal cavity drains into the pterygoid plexus (plexus pterygoideus). Lymphatic vessels drain toward the submandibular and submental lymph nodes (nodi lymphoidei submandibulares et submentales).
Innervation of the nasal cavity has a clear zonal distribution:
- Anterior regions are innervated by the anterior ethmoidal nerve (n. ethmoidalis anterior) — a branch of the nasociliary nerve (n. nasociliaris), which arises from the ophthalmic nerve (n. ophthalmicus).
- Posterior regions receive innervation from the posterior nasal nerves (nn. nasales posteriores) — branches of the maxillary nerve (n. maxillaris), passing through the pterygopalatine ganglion (ganglion pterygopalatinum).